The results of the protein and immunohistochemistry analyses showed that the combination of vemurafenib and melatonin not only predominantly suppressed the expression of hTERT, inducible nitric oxide synthase (iNOS), p65, CD44, and the epithelial cellular adhesion molecule (Epcam), but also markedly reduced the level of proliferating cell nuclear antigen (PCNA) in tumor xenografts, compared with the single drug treatment. Here, PCNA is linked to neoplasm.